Roll wear is a key factor in improving mill output. During hot rolling of long steel products, the passform surface(s) of the roll becomes worn. Once worn, each passform must be re-ground and then the roll put back into service. This process is repeated until the passform depth reaches a point referred to as the ‘scrap diameter’ meaning that the roll can no longer be used. Referring to FIG. 1, the scrap diameter 12 of a roll 10 is approximately halfway between an outer diameter 14 and an inner diameter 16 with the remaining material 18 below the scrap diameter (scrap diameter to inner diameter) remaining unused.
Being virgin material, this represents a significant cost, so if this portion of the roll could be replaced with a lower cost recycled material then this would reduce the cost of a roll. For example, a standard 8″ diameter roll uses approximately 25 kg of powder with the mass of unused material accounting for approximately 10.5 kg.